A prenatal diagnosis was performed in a family with salt-wasting type of 21-hydroxylase deficiency (21-OHD). A trial of DNA diagnosis in the family, including a
patient, did not reveal informative data when DNAs were restricted with TaqⅠ and hybridized with pC21/3c probe. The level of 17-OHP in the amnion was within a normal range. A girl was born without clinical symptoms. One HLA haplotype which was detected in the patient was inherited from the father. With a view to increasing the number of Japanese families which are proceeded to prenatal DNA diagnosis, it is expected that a beneficial combination with a small number of intragenic RFLPs and/or extragenic RFLPs close to the gene will be established and widely used. Hereafter, prenatal diagnosis in early pregnany will be important for families with 21-OHD.